There is often a need to wrap elongated objects with a web material. For example, elongated hollow cylindrical cores are wrapped with cellulosic web material of limited crepe to create rolls of toilet tissue or paper towels. Other cores might be wrapped with plastic film to create rolls of cling wrap. In such cases the core, and the resulting wrapped roll can be considered as being symmetrical, as the core (or the object being wrapped) has essentially a circular cross-section relative to the central longitudinal axis of the core.
There is also a need to wrap elongated objects which might be considered as being transversely asymmetrical in that such objects have a non-circular cross-section relative to a longitudinal axis thereof. Statues, lamp bases and other such objects, for example, may have to be wrapped in web material to protect such objects during handling, storage or shipping.
U.S. Pat. No. 4,838,169 of June 13, 1989 teaches an asymmetrical runner for a SAILRAIL (trade mark) air conveyor system wherein the core of the runner has generally a D-shaped cross-section. That core must be wound or wrapped with a continuous length of extensible cellulosic web material to a thickness of about 2.5 cm. It is desirable that the web material be wound on the core with uniform tension and this is difficult to do, due in part to the non-circular cross-section of the core. Although the core may rotate at a constant angular velocity, the instantaneous velocity of the wrapped core at the point thereon where it contacts the web material will differ peripherally due to variations in the distance of such point to the axis of core rotation. This in turn causes increases and decreases in web velocity or acceleration at the core periphery and in wound web tension about an average value and such differences in velocity and tension can cause web breakage during winding or can affect the degree of compressibility (hardness) of the wound web material and hence the performance of a runner using the wound core. It is therefore desirable to provide apparatus which will compensate for the differences in web velocity and tension which occur when wrapping a web material on an object, particularly an object which is noncircular with respect to a rotation axis thereof.